* fix: pin python-slugify<5.0.0
transifex-client requires python-slugify<5.0.0 for Python 2.0 support which conflicts with the latest python-slugify version.

[VAN-437] - Unlocking the learners upon successful password reset

* Commits:
  docs: Remove completed TODO discussions item
  feat: Add support to Discussions API for legacy cohort settings
  refactor: Remove get_course_discussion_settings helper
  refactor: Remove set_course_discussion_settings helper
  refactor: Add better DRF support to legacy discussions settings

fix: Add callback function to Facebook share

so that we can re-use the existing serializer as a portability-shim in
the new API.

Facebook requires a callback when using the `.ui()` method now. I don't
know when this changed, but the share button is currently broken on
course certificates.

Facebook documentation of the `.ui()` method:
https://developers.facebook.com/docs/javascript/reference/FB.ui/

feat: add pacing info in course enrollment serializer

In dfb80acc, we allowed group_access settings to bubble up from
Units to Sequences in the case where all Units had the same group
settings for a particular user partition. This caused an issue
where the group being bubbled up could be empty if the Unit was
misconfigured in OLX (this is already caught if done directly on
the Sequence). This commit fixes things so that empty partition
group settings never bubble up.

We don't want empty partition groups to bubble up because it would
mean that no groups are allowed to access the Sequence, which is
probably an error. (There is a separate visible_to_staff_only flag
when you want to hide content from all non-staff users.)

We can get the same information much more cheaply and predictably
by using CourseOverviews. This was contributing to slow traces for
the edx_proctoring.views:StudentOnboardingStatusView.get
transaction.

feat: AA-775: add course start and pacing to enrollment.activated segment event

fix: fix issue where we were not generating a certificate `verify_uuid` when needed

NOTE: This will require a forced backfill of course outlines to update
the course content data in learning_sequences:

  python manage.py cms backfill_course_outlines --force

Without this backfill, the learning_sequences API will continue to serve
stale content data that has no user partition group data. It won't cause
errors, but it won't do the exclusions properly.

Commit summary:

* Created EnrollmentTrackPartitionGroupsOutlineProcessor to process the
  enrollment_track User Partition Group, allowing Sequences and Sections
  to be removed based on their group_access settings.
* Added user_partition_groups attribute to CourseLearningSequenceData
  and CourseSectionData in learning_sequences/data.py, along with
  backing model data.
* get_outline_from_modulestore now extracts group_access settings from
  Sections and Sequences. It also bubbles up group_access settings from
  Units, meaning that if a Sequence with no group_access setting has
  Units that are all set to show only to the Verified enrollment track,
  then the Sequence will only show to the Verified enrollment track.

This commit adds model-level support for all user partition groups by
capturing all the content group associations (group_access), but it only
implements the code checks for the enrollment track partition. It's not
clear that we want to generalize, since there's only one other partition
type (A/B testing) that is applicable at the outline level.

It's important to note that there is no way to set the group_access for
a Section or Sequence in Studio today. It's only possible by direct
editing of the OLX for import. That being said, the block structures
framework supports applying course groups at this level, and this commit
moves learning_sequences closer to feature parity.

The bubbling up from Units to the parent Sequence was done to mitigate
confusion when a Sequence is entirely composed of Units that are not
visible to the user because of content group restrictions. It's not
clear whether this is something we want to do in the long term, since it
would simplify the code to always specify group_access at the Sequence
level. This first pass is done partially to collect better data about
places in our courses where this kind of usage is already happening.

Most of the EnrollmentTrackPartitionGroupsOutlineProcessor code and its
tests were written by @schenedx.

[MICROBA-1181]
- change how we determine if we need to generate a verify_uuid for a learner's certificate record

* docs: fix formatting inconsistencies in grade data model docs

* docs: add subsection grade override model

* docs: add gradebbook info to grades / background

* docs: fix formatting issues in grades / background

Since the ENABLE_COURSEWARE_MICROFRONTEND Django setting
was removed, the "View in New Experience" button began
to always appear in Legacy courseware for global staff
members in *all* environments.

This was OK for edx.org's purposes, since the Learning MFE
is deployed in all of our production environments.
However, many (perhaps most) Lilac Open edX instances will
*not* deploy the Learning MFE. So, we need to make sure that
this button is not shown by default.

Since we cannot programmatically tell from LMS whether
or not the Learning MFE is deployed, we will depend on
the value of the `courseware.microfrontend_course_team_preview`
flag, which is already being used to decide whether
course staff can see the "View in New Experience" button.

Whether or not the button is shown, global staff will
still be permitted to browse courses in the Learning
MFE if it is deployed.

https://github.com/openedx/build-test-release-wg/issues/49

DEPR-140 MICROBA-985

fix: Clean up old errors from certificate records now in `downloadable` status

[AA-721] Add necessary data for new progress page

* Commits:
  feat: Add support for legacy discussions settings to API
  test: Add CourseFactory to discussions API tests

* Change order of object Manager declarations in the GeneratedCertificate model. Declaration order matters and It appears that having the "base" `objects` declaration after the other Custom Managers creates an issue where I cannot access `objects` in a migration without this change.
* As part of the manager migration there is a cleanup function that resets the `error_reason` field to an empty string for all certificates in the `downloadable` state that currently have an error listed in the record.